:I do not understand

I do not get the :I face. Is it meant to be some sort of face which represents meh-ness? Or bemusement? Confusion? About to barf? And if so, does it work outside the Times New Roman font? Things are moving too quickly for me. My sister's using it, and I'm still trying to figure out what it means.

My awesome Ugg Boots also arrived today, but alas, mother ordered them a size too small. Thus, I am tromping around everywhere with them on in the possibly-vain hope that they will magically expand. My feet are pressuring them like a mob boss who wants to know something, and hopefully they, like the helpless hostages they are meant to be, will crack under said pressure. That's the plan anyway. Don't know how effective it may, or may not, be. And my last post was very long, and exceeded the tag limit of 200 characters. Shall go tag it now, and only do the what I deem to be important ones.